A policy of engagement with North Korea is the only viable option to resolve the North's nuclear weapons programs, but Seoul and Washington must set "strict standards" to prevent Pyongyang from backsliding and repeating its nuclear hide-and-seek, a former U.S. point man on North Korea said Tuesday.

Stephen Bosworth, the Obama administration's first special envoy for North Korea, also expressed skepticism that China, the North's key ally and economic benefactor, would wield an enough leverage to persuade Pyongyang to give up its nuclear ambition.

Washington's policy of deterring North Korea did not work, as Pyongyang conducted its second nuclear test in 2009 and revealed a uranium enrichment program in 2010 that could give it another means of producing fissile material for nuclear bombs. In 2010, North Korea launched two military attacks on South Korea.

"So, I think we have no choice but to re-engage ourselves (with North Korea)," Bosworth told a forum in Seoul.

To bring about positive changes in Pyongyang's behavior, Bosworth said Seoul and Washington need "a very careful diplomacy, patience and willingness, not simply to give to North Korea, but to set strict standards."

Bosworth was the top U.S. envoy for North Korea from March 2009 to October 2011. He also served as U.S. ambassador to South Korea and is now dean of the Fletcher School at Tufts University.

Diplomatic efforts to resume the six-party talks on ending North Korea's nuclear ambition have been frozen since April, when North Korea defiantly launched a long-range rocket that failed moments after lift-off.

The defiant launch drew strong condemnation from the U.N. Security Council as a disguised test of ballistic missile technology, and led to the collapse of the so-called "Leap Day" deal with the U.S., under which Washington would resume food aid to Pyongyang in return for a monitored shutdown of the North's nuclear activities.

Although North Korea reneged on the deal, Bosworth expected Korea and the U.S. to resume their engagement with Pyongyang after their presidential elections this year.

U.S. President Barack Obama has been in a tight race for re-election in November against Republican rival Mitt Romney, while South Korea is set for its presidential vote in December.

"I'm assuming that after our elections are over, we'll have newly elected governments in place here in South Korea and the United States. Then, attention will turn again to the question of how we will deal with North Korea," Bosworth said.

Bosworth warned that destabilizing North Korea could have serious consequences for the global economy.

"Northeast Asia is now becoming the center of the global economy," he said. "A severe disruption of stability in Northeast Asia will have profound consequences not just for this region, but the global economy." (Yonhap)